Timers using sand, liquid, or other flowing media are well known in the prior art, and are exemplified in the patent of Ira E. McGehee, U.S. Pat. No. 2,199,645, and the centuries-old sand hourglasses.
The McGehee U.S. Pat. No. 2,199,645 discloses a flowing medium timing device that provides for one particular timing interval and the capability of resetting that interval whether or not the timing medium has completed its passage through the restricting orifice. This resetting feature teaches that the timing medium may be totally collected at any point in the timing sequence by revolving the timer 360.degree. so that all the timing medium merges and is made instantly available for another timing sequence. Thus the timer is designed for instant resettability for a one time-interval determined by the total amount of the timing medium encased therein.
Further, it has been taught by Hemperly, U.S. Pat. No. 4,408,894 that single, partial portions of timing medium may be loaded or removed for a pre-determined timing interval by rotating the timing device 360.degree. for each portion to be added to or subtracted from the total quantity of timing medium to be used for a specified timing interval.
It is desireable that a flowing-medium timing device be made available that can be used to measure more than one time interval and also be instantly resettable to each and every one of those timing modes whether or not the previous timing interval has been completed.